With the recent demand for precision machining in the field of cutting processes, development of high-performance cutting tools is urgently needed to perform elaborate perforation without additionally performing a subsequent process, such as a finishing operation.
In the cutting process, a centripetal property of a cutting tool can be improved by a high degree of precision in a perforation process, leading to improvement in the precision in view of hole size and shape. The centripetal property of the cutting tool can be improved by reducing a point angle.
However, when the point angle of the cutting tool is reduced, the rigidity of its cutting portion may be undesirably lowered, ultimately resulting in an increased torque of the cutting tool during the cutting process.
In addition, when the cutting tool having a small point angle passes through a to-be-cut material, the size of a burr generated in the perforation process may increase.